Method of automatically grading articles, in particular, garments

ABSTRACT

For an article of a given type, in particular a garment, a grading mask is used that has images of the pieces of a reference article, geometrical grading regions, each of which contains one or more characteristic points of a piece of the reference article, and grading formulae associated with respective ones of the various regions, each grading formula making it possible, in the associated grading region, and as a function of the variation in one or more magnitudes of a scale of measurements, or of a predetermined increment value, to determine a displacement to be applied to each characteristic point contained in said region for going from the base size to another size. Images of the pieces of the article to be graded for an article size corresponding to the base size of the grading mask are called up, said images are placed on the grading mask in positions corresponding to the positions of the pieces of the mask, and the pieces are graded automatically on the basis of the grading formulae of the mask and of a chosen scale of measurements.

BACKGROUND OF THE INVENTION

The present invention relates to a method of grading an article of agiven type, in particular a garment, formed by assembling a plurality ofpieces.

Garments are generally made by assembling a plurality of pieces whichcorrespond to a base model or pattern and each of which is in the formof a plane developed area having a particular outline and optionallycertain additional internal markers.

The size of a garment is determined mainly relative to particularmeasurements such as chest size, neck size, hip size, etc., and by thestyle that is to be given to the garment (tight-fitting or loose-fittingstyle, for example). The various measurements are organized into scalesof sizes or tables of measurements which differ depending on thetargeted population.

For each piece of a garment, grading is thus the operation that consistsin obtaining, from a base model corresponding to a base size, additionalpatterns that are of different (larger or smaller) sizes as a functionof a given scale of measurements, but that remain similar, as regardstheir shapes, to the base model.

Grading then makes it possible to obtain the geometrical layouts of thepieces in the various sizes, which is necessary for preparing to cut thepieces out from the material out of which the garment is to be made,which material can, for example, be a woven fabric, leather, or anyother desired natural or synthetic material.

Grading also applies to all of the other fields in which articles ofdifferent sizes are made that must correspond to a base model, such as,for example, the field of shoemaking.

When grading is applied to a garment, it is already known thatcharacteristic points or “outline points” can be marked on the pieces ofthe base model, knowledge of the outline points making it possible toreconstruct, in full, the images of the pieces, optionally also withmarkers internal to said pieces.

For each different size, grading thus consists in determining thecharacteristic points corresponding to the characteristic points of thebase model, and in applying grading rules with reference to a givenscale of measurements. On the basis of the characteristic pointsdetermined in this way, the image of the base model for the size inquestion can be plotted automatically, which enables automaticcutting-out to be performed subsequently.

Since numerous grading rules exist for each type of garment and for eachscale of measurements, the main difficulty in applying such a methodlies in choosing the proper grading rule for each characteristic pointof each piece of the garment, on the basis of a given base size. Often,the knowledge and know-how of experienced staff is used.

OBJECT AND SUMMARY OF THE INVENTION

An object of the invention is precisely to remedy such drawbacks byproposing a method that is simple to use and that enables articles to begraded automatically, for various sizes and regardless of the chosenscale of measurements.

According to the invention, these objects are achieved by means of amethod characterized in that it consists in: using a grading mask havingimages of the pieces of a reference article of the same type as the typeof the article to be graded and for a given base size, a plurality ofgeometrical grading regions, each of which contains one or morecharacteristic points of a piece of the reference article, and gradingformulae associated with respective ones of the various regions, eachgrading formula making it possible, in the associated grading region,and as a function of the variation in one or more magnitudes of a scaleof measurements, or of a predetermined increment value, to determine adisplacement to be applied to the or to each characteristic pointcontained in said region for going from the base size to another size;calling up the images of the pieces of the article to be graded for anarticle size corresponding to the base size of the grading mask; placingthe images of the pieces of the article to be graded on the grading maskin positions corresponding to the positions of the pieces of the mask;and automatically grading the pieces of the article to be graded on thebasis of the grading formulae of the mask and of a chosen scale ofmeasurements for the article to be graded.

The method of the invention thus offers numerous advantages. Inparticular, it is automatic and simple to use; apart from the images ofthe pieces of the article to be graded, from the chosen scale ofmeasurements, and from the existing grading mask, no other element isnecessary for implementing it. In addition, the same grading methodestablished for a given style of article can be applied to styles thatare similar to it, and to various scales of measurements. By expressingthe grading steps in a visual and geometrical mode, the method alsomakes it possible to see how applying the grading formulae of the scaleof measurements affects the grading of each piece of the article.

According to a particular characteristic of the invention, when acharacteristic point of a piece of the article to be graded is includedin a plurality of grading regions of the grading mask, the gradingformulae of each of said grading regions apply cumulatively to saidcharacteristic point.

The step of placing the images of the pieces of the article to be gradedin correspondence with the images of the pieces of the grading mask isfollowed by revising one or more grading regions of the mask so thateach grading region that includes a characteristic point of a piece ofthe mask also includes the corresponding characteristic point of thearticle to be graded.

In order to comply with certain particular constraints of the article tobe graded, it is possible to use a grading mask that also includes oneor more special grading regions, each of which includes an outlineportion of a piece of the mask and at least one special grading formulaassociated with each special grading region and specifying a constraintto be applied to the portion of the outline during the grading, and,during the grading, the special grading formula associated with aspecial grading region that contains one or more outline portions of thepiece of the article to be graded is applied to the or to each outlineportion.

In which case, the special grading formula expresses a constraint chosenfrom at least one of the following outline portion constraints: shapeconstraint, length constraint, and orientation constraint.

The invention also provides a method of creating a grading mask, saidmethod being characterized in that it consists in: using images of thepieces of a reference article of this type for a given base size;positioning the images of the pieces of the article in a plane; creatinggrading regions, each of the grading regions being defined by ageometrical zone of the plane and containing at least one characteristicpoint of a piece of the article; and associating each grading regionwith a grading formula making it possible, in the associated gradingregion, and as a function of the variation in one or more magnitudes ofa scale of measurements, or of a predetermined increment value, todetermine a displacement to be applied to the or to each characteristicpoint contained in said region for going from the base size to anothersize.

The invention also provides a grading mask characterized in that it hasimages of the pieces of a reference article of the same type as the typeof the article to be graded and for a given base size, a plurality ofgeometrical grading regions, each of which contains one or morecharacteristic points of a piece of the reference article, and gradingformulae associated with respective ones of the various regions, eachgrading formula making it possible, in the associated grading region,and as a function of the variation in one or more magnitudes of a scaleof measurements, or of a predetermined increment value, to determine adisplacement to be applied to the or to each characteristic pointcontained in said region for going from the base size to another size.

The invention also provides a set of grading masks as defined above, thegrading masks being in a digital form.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the present invention appearfrom the following description given with reference to the accompanyingdrawings which show an implementation of the invention that is notlimiting in any way. In the figures:

FIG. 1 is a flow chart showing various steps in implementing a gradingmethod of the invention;

FIG. 2 is a flow chart showing various steps in implementing a method ofcreating a grading mask of the invention; and

FIGS. 3 to 7 show various steps in the grading method of the inventionas applied to the example of a shirt.

DETAILED DESCRIPTION OF AN IMPLEMENTATION

In the following description, consideration is given to grading thepieces of a garment. However, the invention is also applicable tograding pieces of articles other than garments, e.g. shoes or otherfootwear, which are also made in different sizes that are to correspondto a base model.

Grading Method

Reference is made firstly to FIG. 1 which shows the steps in aparticular implementation of a grading method of the invention.

In general, the grading method of the invention can be implemented bymeans of a computer system equipped, in particular with a graphicsworkstation and with grading software. The graphics workstation can beof the same type as computer-aided design (CAD) software for designinggarments.

In a first step (10) of the method, the operator searches for and uses agrading mask having images of the pieces of a reference garment of thesame type as the garment to be graded for a given base size.

The grading mask, whose creation method is described below, also has aplurality of grading geometrical regions, each of which contains one ormore characteristic points that are characteristic of a piece of thereference garment, and grading formulae associated with respective onesof the different regions.

Inside the associated grading region, and as a function of the variationof one or more magnitudes of a scale of measurements or of apredetermined increment value, each grading formula makes it possible todetermine a displacement to apply to the or to each characteristic pointcontained in said region in order to go from the base size to anothersize.

The grading mask can also have one or more special grading regions, eachof which includes a portion of the outline of a piece of the mask and atleast one special grading formula associated with each special gradingregion and specifying a constraint to be applied to the portion of theoutline during grading.

In order to help the operator in searching for the grading mask to beused, the images of the pieces of the reference garment that arecontained in the mask can be positioned in a plane in relative positionsthat are substantially similar to their assembly positions for formingthe article.

The grading mask is advantageously in a digital form that can be stored,e.g. in a database of the grading computer system.

The following step (12) consists in displaying, e.g. on the screen ofthe workstation, the grading mask to be used (i.e. the images of thepieces of the reference garment and the grading geometrical regions thatare associated with them).

During another step (14) of the grading method, the operator calls up,e.g. onto the screen of the workstation, images of the pieces of thegarment to be graded for a garment size corresponding to the base sizeof the grading mask.

In a manner known per se, the images of the pieces of the garment to begraded are produced while designing the garment, in particular by usinga CAD system. They are also in digital form and are stored in a memoryor in a database of the graphics workstation.

The following step (16) of the method consists, for the operator, inplacing the images of the pieces of the garment to be graded on thegrading mask in positions corresponding to the positions of the piecesof the reference article contained in the mask.

This operation (16) of superposing images can be performed manually bythe operator, e.g. by means of a suitable tool of the mouse type. Itconsists in causing the positions of the pieces of the garment that isto be graded to correspond as closely as possible with the positions ofthe pieces of the grading mask.

The names of the characteristic points of the pieces of the garment tobe graded can already be included in the digital images called up on theworkstation. They can also be assigned by the operator by matching withthe names of the pieces of the reference garment when the images havebeen superposed.

The superposition operation can also be performed automatically by amethod optionally also making it possible to assign names to thecharacteristic points of the pieces of the garment to be graded so thatthey match the names of the characteristic points of the pieces of thegrading mask.

In practice, such a method consists, for the operator, in placing theimages of the pieces of the garment to be graded substantially incorrespondence with the pieces of the grading mask. A computer routineinvolving convolution analyzes the sequence of the consecutive anglesand relative side lengths of the segments of the pieces in order todetermine the best superposition of the pieces of the garment to begraded on the pieces of the grading mask. On the basis of these relativepositions of the pieces, the names of the characteristic points can beassigned automatically to the pieces of the garment to be graded bymeans of proximity and by angular interval value.

If necessary, the step (16) of placing the images of the pieces of thegarment to be graded in correspondence with the images of the pieces ofthe grading mask can be followed by revising one or more grading regionsof the mask so that each grading region that includes a characteristicpoint of a piece of the mask also includes the correspondingcharacteristic point of the corresponding piece of the article to begraded (step 18).

The step (18) of revising the grading regions of the mask can beperformed manually by the operator, e.g. by selecting, by means of amouse, the various grading regions that are to be modified.

Once the images of the pieces of the garment to be graded are correctlypositioned on the grading mask, the last step (20) of the grading methodconsists in automatically performing the grading proper of the pieces ofthe garment to be graded.

The grading (20) is performed on the basis of the grading formulae ofthe mask and of a scale of measurements chosen for the garment to begraded.

Optionally, during the grading (20), a special grading formulaassociated with a special grading region is applied to the or eachoutline portion of the piece of the garment to be graded that iscontained in said special grading region.

Provision can be made during the grading step (20) for automaticallyadjusting the way the images of the pieces of the garment are disposedrelative to one another, in particular in order to avoid said piecesoverlapping when grading a garment to a size larger than the size of thereference garment.

Grading Mask

The various steps in the method of creating a grading mask of theinvention are described below with reference to FIGS. 2 and 3.

FIG. 2 shows the steps of a particular implementation of the method ofcreating a grading mask.

FIG. 3 shows a fragmentary example of a grading mask for a referenceshirt having a given base size.

As in the grading method of the invention, the method of creating agrading mask can be implemented by means of a computer system equippedin particular with a graphics workstation and with grading software.

In a first step (22) of the method, use is made of images of the piecesof a reference garment of a given type for a given base size.

In the example in FIG. 3, the reference garment is a shirt 100′. Theshirt is made up of various pieces, and in particular of a front piece102′, of a back piece 104′, of a sleeve 106′, and of an “armseye” orarmhole piece 108′.

Each of the pieces of the reference shirt is defined by itscharacteristic points or “outline points”, knowledge of which makes itpossible to reconstruct the image in full.

For example, the outline of the front piece 102′ is identified by itscharacteristic points P′44 to P′53.

The images of the pieces of the reference garment are displayed, e.g. onthe screen of the workstation of the grading computer system, and theyare positioned in a plane (step 24).

As shown in FIG. 3, the images of the pieces of the reference shirt canbe positioned in the plane in positions substantially similar to theirassembly positions for forming the shirt.

The next step (26) of the method consists in creating grading regions,each of which is defined by a geometrical zone of the plane, and each ofwhich contains at least one characteristic point of a piece of thereference garment.

The geometrical zones of the grading regions can be defined by polygonalshapes (e.g. rectangles), by two concurrent straight lines or by asingle straight line defining a half-plane.

They are created visually by the operator, e.g. by means of the graphicsworkstation of the grading computer system.

In the example shown in FIG. 3, the grading regions of the mask areshown diagrammatically, but only for the front piece 102′ of thereference shirt 100′. Said regions are shown as dashed-line rectangles110′ to 114′.

Each of the grading regions 110′ to 114′ contains at least onecharacteristic point of the piece 102′.

It can be observed that the same characteristic point of the piece 102′can be contained in a plurality of different grading regions (thisapplies in particular to points P′48, P′49, and P′53).

Similarly, certain characteristic points, such as P′45 and P′46 canbelong to none of the grading regions.

In the next step (28) of the method of creating the mask, each gradingregion is associated with a grading formula making it possible, in theassociated grading region and as a function of the variation of one ormore magnitudes of a scale of measurements or of a predeterminedincrement value, to determine a displacement to be applied to the or toeach characteristic point contained in said region for going from thebase size to another size.

The grading formulae associated with the grading regions are createdusing the measurement mnemonics of a measurement scale.

In the example of FIG. 3, such grading formulae that are associated withrespective ones of the grading regions of the front piece 102′ are alsoshown in rectangles 110′ to 114′.

For example, for the grading region 111′, the grading formula is Δ/2 andit is associated with a grading direction (shown by a displacementvector).

The grading formulae ΔC/2 refers to a chosen scale of measurements, and,in this particular case, it specifies that all of the characteristicpoints of the piece to be graded that are contained in the gradingregion 111′ must be incremented, depending on the value of the basesize, and in the direction represented by the displacement vector by onehalf of the variation (Δ) of the value of the “Chest” measurementindicated in the scale.

The following table is an example showing part of a scale ofmeasurements for a targeted population, and that makes it possible togive a practical example of how such a grading formula is applied.

SIZES Name Measurement 36 38 40 42 44 46 48 L1 L2 L3 L5 L6 C Chest 465489 512 518 524 539 536 N Neck 223 229 238 241 248 245 260 L Length 772758 794 801 807 814 820 LC Length 20 10 0 10 20 configuration

The starting assumption is that the reference shirt is size 40 (with alength corresponding to the size L3), and that it is desired to obtain ashirt of size 42.

The grading formula ΔC/2 for the grading region 111′ thus indicates thatall of the characteristic points of the piece to be graded that areincluded in said region must be incremented “downwards” by the value(518−512)/2, i.e. 3.

Similarly, since the grading formula for the region 114′ is ΔC/3associated with a displacement vector, all of the characteristic pointsof the piece to be graded and included in said region are incremented“rightwards” by the value (518−512)/3 i.e. 2.

It should be noted that the grading formula of the region 110′ is ALCassociated with a displacement vector. For the same base size (size 40in this example), such a grading formula makes it possible to obtain aplurality of possible shirt lengths represented in the scale ofmeasurements by respective ones of the values L1, L2, L3, L5, and L6.

It should also be noted that, since the point P′53 belongs to twograding regions 110′ and 111′, the characteristic point of the piece tobe graded is graded simultaneously both by the grading formula ΔC/2associated with its grading direction, and by the grading formula ΔLCassociated with its displacement vector.

The grading mask can thus have one or more grading regions, the gradingformula of each region being a function of a predetermined incrementvalue. In the example of FIG. 3, the grading regions are grading regions112′ and 113′ for which the respective grading formulae are “5” and “9”,each of which is associated with a displacement vector.

Thus, for the region 112′, the grading formula “5” indicates that theamplitude of the displacement of all of the characteristic points of thepiece to be graded and contained in said region corresponds, for gradingbetween two consecutive sizes, to the predetermined value of 5millimeters (mm) and to the direction represented by the displacementvector.

In addition, in the example shown in FIG. 3, the grading directionsassociated with the various grading formulae are represented bydisplacement vectors that correspond to grading the front piece 104′ fora size larger than the size of the reference piece.

If it is desired to grade the piece to a size smaller than the size ofthe reference piece, an angle of 180° should be assigned to saiddisplacement vectors. More generally, when the increment differencebetween the size to be reached and the size of the reference piece isnegative, an angle of 180° should be assigned to the displacementvectors shown in FIG. 3.

Thus, if it is desired to obtain a shirt of size 38 (corresponding tosize L2), all of the characteristic points of the piece to be graded andincluded in the region 114′ are incremented “leftwards” by the value 2.

It is also possible to create one or more special grading regions, eachof which includes a portion of the outline of a piece of the mask (step30).

Each of the special grading regions is associated with a special gradingformula specifying a constraint to be applied to the portion of theoutline during grading (step 32).

For example, the constraint to be applied to the portion of the outlinecan be a shape, length, or orientation constraint.

The characteristic points of the piece to be graded that are includedboth in a special grading region and in an above-defined standardgrading region are graded independently using the respective gradingprocedures (special and standard).

An example of a special grading region is explained below with referenceto FIG. 3.

For such a reference shirt, special grading regions can be created forthe outline portions of the front piece 102′ and of the back piece 104′that lie respectively in the range defined by points P′49 to P′51 and inthe range defined by points P′4 to P′6 (corresponding to the armholes ofthe shirt), for the portion of the outline of the sleeve 106′ that liesin the range defined by points P′17 to P′23, and for the portion of theoutline of the armhole piece 108′ defined by points P′57 to P′59.

For example, these special grading regions can be associated with thefollowing special grading formulae:L(P′17, P′20)=L(P′51, P′49)  (1)L(P′20, P′23)=L(P′4, P′6)+L(P′57, P′59)  (2)

Formula (1) thus specifies that the portion of the sleeve of the shirtto be graded that lies in the range defined by points P′17 to P′20 ofthe mask should, on being graded, and for each size, keep the samelength proportion as the length proportion known for the base size.

Similarly, formula (2) indicates that the shape of the sleeve of theshirt to be graded that lies in the range defined by points P′20 to P′23of the mask should, on being graded, and for each size, have the samelength proportion as the corresponding length defined by points P′6 toP′4 of the back piece in the same size, plus the length defined bypoints P′57 to P′59 of the armhole piece.

Another example of a special grading formula is as follows:R(P′a, P′b, P′c, direction, parameter)  (3)

Such a formula (3) indicates that the portion of the outline of thepiece to be graded that lies in the range defined by points P′a and P′bof the mask should, on being graded, be subjected to rotation about apoint P′c in a specified direction (clockwise or counterclockwise)through a number of degrees indicated by the parameter.

This type of formula (3) can be necessary when, for example, gradingdarts in a garment, the angle at the points of the darts changing withchanging size by a constant quantity per size or as a function of one ofthe measurements of the body.

The resulting grading mask can then be stored (step 34), e.g. in digitalform, in a database of the grading computer system containing a set ofgrading masks each associated with a particular reference garment.

Example of Application of the Grading Method

This example relates to automatically grading a shirt formed byassembling a plurality of pieces.

Above-described FIG. 3 shows a fragmentary example of a grading maskthat can be applied to grading such a shirt.

FIG. 4 shows an example of an image of the shirt to be graded. In FIG.4, the shirt 100 is made up of various pieces, and, in particular, of afront piece 102, of a back piece 104, of a sleeve 106, and of an armholepiece 108, each of the pieces having characteristic points.

In this example, the various component pieces of the shirt arepositioned in a plane in relative positions similar to the positions inwhich they are assembled to form the shirt.

In the first step (10) of the grading method, the operator uses thegrading mask of FIG. 3 which has images of the pieces of the referenceshirt of the same type as the shirt to be graded.

The step (16) of placing the images of the pieces of the shirt to begraded on the grading mask in positions corresponding to the positionsof the pieces of the mask is shown in FIG. 5.

For reasons of clarity, the figures show only the placing of the imageof the front piece 102 of the shirt to be graded on the correspondingpiece 102′ of the reference shirt contained in the mask.

In this embodiment, the superposition of the piece 102 on the piece 102′of the grading mask is not perfect.

Certain characteristic points of the front piece 102 of the shirt to begraded are not included in the grading regions of the mask that areassigned to them. This applies in particular to points P44 and P55 thatare to be associated with the grading region 110′ of the mask, to pointP52 of the grading region 111′, and to point P42 of the grading region114′.

The step (18) of revising one or more grading regions of the mask makesit possible to solve this problem by making provision for the gradingregions 110′, 111′, and 114′ of the mask also to include the respectivecharacteristic points P44, P54, P52, and P47 of the front piece 102 ofthe shirt to be graded.

FIG. 6 shows an implementation of such a step of revising the gradingregions.

In FIG. 6, the grading regions 110′, 111′ and 114′ of the mask have thusbeen revised so as to be enlarged to include respective ones of thecharacteristic points P44, P54, p 52, and P47 of the front piece 102.

Once the images of the front pieces 104 of the shirt to be graded havebeen positioned correctly on the grading mask, the front piece 104 canbe graded automatically.

FIG. 7 shows an example of the result of grading obtained for the frontpiece 104 of the shirt when grading to a size larger than the base sizeof the reference shirt. The outline of the piece in dashed lines showsthe base size and the outline of the piece in uninterrupted lines showsthe larger size obtained.

Thus, only the creation of the grading masks for the various types ofgarment requires the know-how and knowledge of experiencedprofessionals. A mask that is pre-established for one type of garmentcan then be used very easily without needing any particular expertise.

1. A method of automatically grading an article of a given type, inparticular an article of a garment type, that is formed by assembling aplurality of pieces, said method comprising: using a grading mask havingimages of the pieces of a reference article of the same type as the typeof the article to be graded and for a given base size, a plurality ofgeometrical grading regions, each of which contains one or morecharacteristic points of a piece of the reference article, and gradingformulae associated with respective ones of the various regions, eachgrading formula making it possible, in the associated grading region,and as a function of the variation in one or more magnitudes of a scaleof measurements, or of a predetermined increment value, to determine adisplacement to be applied to each characteristic point contained insaid region for going from the base size to another size; calling up theimages of the pieces of the article to be graded for an article sizecorresponding to the base size of the grading mask; placing the imagesof the pieces of the article to be graded on the grading mask inpositions corresponding to the positions of the pieces of the mask; andautomatically grading the pieces of the article to be graded on thebasis of the grading formulae of the mask and of a chosen scale ofmeasurements for the article to be graded.
 2. The method according toclaim 1, wherein the one or more characteristic points of the piece ofthe article to be graded is included in the plurality of grading regionsof the grading mask, the grading formulae of each of said gradingregions apply cumulatively to the one or more characteristic points. 3.The method according to claim 2, wherein the step of placing the imagesof the pieces of the article to be graded in correspondence with theimages of the pieces of the grading mask is followed by revising one ormore of the grading regions of the mask so that each grading region thatincludes the one or more characteristic points of the piece of the maskalso includes the corresponding one or more characteristic points of thearticle to be graded.
 4. The method according to claim 2, wherein thegrading mask also includes one or more special grading regions, each ofwhich includes an outline portion of a piece of the grading mask and atleast one special grading formula associated with each special gradingregion and specifying a constraint to be applied to the portion of theoutline during the grading, and, during the grading, the special gradingformula associated with a special grading region that contains one ormore outline portions of the piece of the article to be graded isapplied to the or to each outline portion.
 5. The method according toclaim 1, wherein the step of placing the images of the pieces of thearticle to be graded in correspondence with the images of the pieces ofthe grading mask is followed by revising one or more of the gradingregions of the mask so that each grading region that includes the one ormore characteristic points of the piece of the mask also includes thecorresponding one or more characteristic points of the article to begraded.
 6. The method according to claim 5, wherein the grading maskalso includes one or more special grading regions, each of whichincludes an outline portion of a piece of the grading mask and at leastone special grading formula associated with each special grading regionand specifying a constraint to be applied to the portion of the outlineduring the grading, and, during the grading, the special grading formulaassociated with a special grading region that contains one or moreoutline portions of the piece of the article to be graded is applied tothe or to each outline portion.
 7. The method according to claim 6,wherein the special grading formula expresses the constraint chosen fromat least one of the following outline portion constraints: shapeconstraint, length constraint, and orientation constraint.
 8. The methodaccording to claims 1, wherein the grading mask also includes one ormore special grading regions, each of which includes an outline portionof a piece of the grading mask and at least one special grading formulaassociated with each special grading region and specifying a constraintto be applied to the portion of the outline during the grading, and,during the grading, the special grading formula associated with aspecial grading region that contains one or more outline portions of thepiece of the article to be graded is applied to the or to each outlineportion.
 9. A method of creating a grading mask for automaticallygrading articles of a given type, in particular articles of a garmenttype, that are formed by assembling a plurality of pieces, said methodcomprising: using images of the pieces of a reference article of thegiven type for a given base size; positioning the images of the piecesof the reference article in a plane; creating grading regions, each ofthe grading regions being defined by a geometrical zone of the plane andcontaining at least one characteristic point of the piece of thearticle; and associating each grading region with a grading formulamaking it possible, in the associated grading region, and as a functionof the variation in one or more magnitudes of a scale of measurements,or of a predetermined increment value, to determine a displacement to beapplied to each characteristic point contained in said region for goingfrom the base size to another size.
 10. The method according to claim 9,wherein the method further comprises creating one or more specialgrading regions, each of which includes a portion of the outline of thepiece of the mask, and in associating each special grading region withat least one special grading formula specifying a constraint to beapplied to the portion of the outline during grading.
 11. A grading maskfor automatically grading articles of a given type, in particulararticles of the garment type, that are formed by assembling a pluralityof pieces, said mask comprising images of the pieces of a referencearticle of the same type as the type of the article to be graded and fora given base size, a plurality of geometrical grading regions, each ofwhich contains one or more characteristic points of the piece of thereference article, and grading formulae associated with respective onesof the various regions, each grading formula making it possible, in theassociated grading region, and as a function of the variation in one ormore magnitudes of a scale of measurements, or of a predeterminedincrement value, to determine a displacement to be applied to eachcharacteristic point contained in said region for going from the basesize to another size.
 12. The grading mask according to claim 11,wherein the grading mask further comprises one or more special gradingregions, each of which includes a portion of an outline of the piece ofthe mask and at least one special grading formula associated with eachspecial grading region and specifying a constraint to be applied to theportion of the outline during the grading.
 13. A set of grading masks asdefined in claim 12, wherein the grading masks comprise digital filesstored in a computer-readable medium.
 14. A set of grading masks asdefined in claim 11, wherein the grading masks comprise digital filesstored in a computer-readable medium.